Since Kodachrome was put on the market by Eastman Kodak Co. in 1935. Various improvements of color photography and enhancements of photographic performance thereof have been still in progress, including fine image structure, that is, enhancements of graininess and sharpness and an enhancement of color reproduction. Of these, with regard to a technique for enhancing color reproduction, there have been marked enhancements of reproducibility in the past, including auto masking colored couplers (as described in U.S. Pat. No. 2,455,170).
The colored coupler is mainly used for enhancing color reproducibility of a color negative film. The colored coupler contributes to correction of unwanted absorption of a magenta or cyan dye. Thus, the colored coupler corrects imagewise color contamination due to unwanted absorption of produced dyes of the color negative film, enabling a marked enhancement of color reproduction. To achieve clear color reproduction, there was proposed development effect or so-called interlayer effect as a technique for enhancing color purity of the color negative film (as described in Belgian Patent 710,344 and German Patent 2,043,934). Furthermore, a DIR coupler as application of the interlayer effect was developed, whereby reproducibility of color purity was markedly enhanced (as described in U.S. Pat. No. 3,277,554).
Thus enhanced chromatic color reproduction is aimed, while there was proposed techniques to faithfully reproduce color as seen by the human eye. One of them concerns control of spectral sensitivity distribution of a blue-sensitive layer, a green-sensitive layer and a red-sensitive layer of a color film, as described in JP-A 5-150411 (hereinafter, the term, JP-A means a unexamined, published Japanese Patent Application).
There were further proposed techniques of enhancing color reproduction, in which differences in spectral sensitivity distribution between cones of the human eye and the color film was noted. The color film generally has a spectral sensitivity distribution such that a blue-sensitive layer has a sensitivity maximum at longer wavelengths, a green-sensitive layer has a sensitivity maxim at slightly longer wavelengths and a red-sensitive layer has a sensitivity maximum at rather longer wavelengths, as compared to the spectral sensitivity distribution of the human eye. Further, red cones of the eye have a region in the vicinity of 500 nm, having negative sensitivity. To allow the spectral sensitivity of the color film to meet the spectral sensitivity of the eye, the spectral sensitivity distribution by use of sensitizing dyes and the interlayer effect by use of a so-called donor layer were controlled, enabling faithful reproduction, to a certain extent, of intermediate colors, which had been hard to reproduce, as described in JP-A 61-34541.
Employing these techniques, color reproducibility of the color film enabled hue of objects to be faithfully reproduced.
As mentioned above, color reproducibility of color photography has steadily been advanced. However, it is still true that with regard to the color photographic materials of the next generation, further enhancement of color reproducibility having different aspects is still desired. The reason for this is that amateur photographers are often still disappointed when they receive their prints. Cited as disappointments are often, when photographing fresh green woods, red flowers and distant mountain ranges. There are numerous photographers, when they have taken such pictures and receive the processed prints, the resulting prints are different from their expectation or from what they had in mind, in which the fresh green color of woods shows dark and dull tones, the fine details of petals of the red flowers is lost, leading to so-called red saturation, and the distant mountain ranges appear to be veiled in mist, losing the three dimensional realism in which they were originally viewed.
Thus, color photography is not satisfactory simply with faithfulness and clearness in color reproduction but it also requires excellent image rendering, which vividly reproduce the scene being photographed.
Japanese Patent Application No. 9-179656 discloses a technique of providing an infrared sensitive layer, information of which was added to visible images to enhance the information amount, enhancing reproduction of a specified color. Although the information amount was thereby markedly enhanced and color reproduction of green leaves was improved, it was also proved that color stability was still unacceptable level. When a red flower was photographed, for example, this infrared sensitive layer was allowed to be photo-sensitized to not only the green leaves but also red petals. It was therefore proved that when the infrared sensitive layer contained a magenta coupler, color reproduction of the red flower was deteriorated and when a cyan coupler was contained therein, color reproduction of the green leaves was deteriorated. It was further proved that when both couplers were contained, both color reproductions were deteriorated. Japanese Patent Application No. 9-8672 discloses a silver halide photographic material, characterized in the photographic material containing a compound having a spectral sensitivity maximum at the wavelengths of 680 to 730 nm and capable of releasing a development inhibitor or its precursor. The object of this disclosure is mainly directed to providing of the interlayer effect of a red sensitive layer to an infrared sensitive and not to an improvement of a specific color reproduction when the infrared sensitive layer is converted to visible images.